Immunological tests for specific diseases, pathogens or allergens are routinely used in hospitals, laboratories, food, drug and environmental control, and are typically carried out by latex agglutination. They constitute a multi-billion dollar industry, which is surging at present due to the increased demand for better health care and environmental quality. These tests are typically preformed by means of latex agglutination assays, a simple and versatile tool for immunodetection (Bangs. L. B., in "Liquid and Surface-Borne Particle Measurement Handbook", Knapp, J. Z., Barber, T. A., Lieberman, A., Eds., Marcel Dekker, N.Y. 1996). These tests however have a number of disadvantages, including the need for relatively large amount of sample, the ambiguous optical readout, and the unsuitability for miniaturization, automation and electronic readout.
While the above drawbacks and the impending computerization of clinical procedures have called for electronic immunosensors, the progress in this area is still quite modest. The sensors available today are either too complex and difficult to use (e.g., based on total internal reflection) or too specific and narrowly oriented (e.g., enzyme catalysis) to be widely usable.
Our invention described here provides general means to replace the agglutination assays used today with high-tech, yet cheap sensors, which can simultaneously test for presence of different molecules in very small samples and give results that are directly read by a computer. The invention is applicable to nearly all of the immunological tests available today, and can be extended to testing for DNA fragments and other genetic markers.